>>510356330 (OP)There's a fine line.
Humans need a certain amount of stimulation. Adversity, excitement, adrenaline, these are good for you. The body and brain are designed to withstand different kinds of stress that would normally occur if we lived out in nature, and because it's kind of built around that, it needs those stresses in order to function properly. They are buttons that regularly need to be pushed to keep the biological engine running.
Those stimuli are missing from modern life and people who are particularly sensitive to this need will likely seek out ways to push those buttons.
But there are also cases of genuine abnormalities in the brain. One example is Alex Honnold, who climbed El Cap without any gear. The part of his brain that normally registers fear doesn't signal properly. He doesn't experience it at all, so for people like him that need those "buttons top be pushed" the threshold is insanely high to push them.